routing plastic

1885 Views 6 Replies 6 Participants Last post by TWheels, Aug 19, 2019

Martyc

Discussion Starter · Aug 16, 2019 (Edited)

I have a 1/2 inch thick rectangular piece of white HDPE that has 4 slots that are 1/4 inch wide by 3 1/2 inches running across the width of the piece. I want to round over the edges of the slots. Any suggestions on how to proceed?

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Stick486

· #2 · Aug 17, 2019

treat it like wood...

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TWheels

· #3 · Aug 17, 2019 (Edited)

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Plastics like HDPE can be worked as if they were wood, as @Stick486 said. However, the feed rate must be much higher in order to avoid melting. If you have scrap try that first. If I were doing what I think you want to do, I would use the following router bit:
https://www.freudtools.com/explore/router-cnc/edge-treatment/ovolo

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1fizgig

· #4 · Aug 17, 2019

Couldn't you treat it a bit like a mortise, but using a bit that'll chamfer both sides and the ends in one pass? Might require a fiddly set up, but it was just a random thought off the top of my head.

Might reduce the amount of heat building up in the bit so it's less likely to melt the plastic as yuo go?

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ger21

· #5 · Aug 17, 2019

Use a point cutting roundover bit, with a template and guide bushing.

Melting should not be an issue at all when cutting roundovers.

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gdonham1

· #6 · Aug 18, 2019

As other have pointed out you have to move right along or you will melt. Do not let the router bit sit too long in one spot. Use a plunge router if you have one and if you have to stall out then lift the router bit up and out. So make a dry run of what you are going to do and keep your router cord out of the way. If you are going to use a jig to guide the router make sure you can make a smooth pass and raise the bit at the ends. If you need to back in to clean up an edge you can do that but keep it moving along.

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TWheels

· #7 · Aug 19, 2019 (Edited)

ger21 said:
Use a point cutting roundover bit, with a template and guide bushing.

Melting should not be an issue at all when cutting roundovers.

@ger21 described exactly how I would carry out the project with one exception, and that is the choice of router bit. I would also heed the advice of @gdonham1 and use a high feed rate in order to avoid melting. My choice of router bit is based on the width of the already existing grooves of which @Martyc wants to round the edges. A point cutting roundover bit would not apply a full 90° roundover in a single pass while an ovolo, a.k.a plunge roundover with a 1/4 inch small diameter would.
While I suggested a Freud ovolo bit, I could not find a Freud point cutting roundover bit!

The two .pdf files linked are exactly the same images as the .png which show the images directly.

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routing plastic

Martyc

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ger21

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